Transactions with Affiliates (Details) - USD ($)					2 Months Ended	3 Months Ended				5 Months Ended	9 Months Ended
		Aug. 23, 2016	Aug. 01, 2016	Jan. 01, 2016	May 16, 2016	Sep. 30, 2016		Sep. 30, 2015		May 16, 2016	Sep. 30, 2016		Sep. 30, 2015		Dec. 31, 2015	Jul. 31, 2015	Jul. 08, 2015
Related Party Transaction [Line Items]
Accounts payable—affiliates						$ 2,598,000					$ 2,598,000				$ 1,962,000
Prepaid assets - affiliates (less than)						1,000					1,000				210,000
Net asset optimization revenues	[2]					108,000	[1]	$ (545,000)	[3]		(42,000)	[1]	$ 1,317,000	[3]
Retail cost of revenues (less than)	[4]					122,830,000	[1]	60,967,000	[3]		248,593,000	[1]	176,000,000	[3]
General and administrative expense - affiliates	[5]					18,009,000	[1]	15,493,000	[3]		55,188,000	[1]	43,909,000	[3]
Proceeds from disgorgement of stockholders short-swing profits						300,000	[6]				$ 941,000	[6]	0	[7]
Tax receivable agreement, net cash savings (as a percent)											15.00%
Tax Receivable Agreement | NuDevco Retail Holdings and NuDevco Retail
Related Party Transaction [Line Items]
Initial TRA payment						1,400,000					$ 1,400,000
Convertible Debt | CenStar | Censtar Convertible Debt
Related Party Transaction [Line Items]
Notes, issued amount																	$ 2,100,000.0
Convertible Debt | Oasis | Oasis Power Holdings Convertible Debt
Related Party Transaction [Line Items]
Notes, issued amount																$ 5,000,000.0
Affiliated Entity
Related Party Transaction [Line Items]
Accounts receivable - affiliates						2,800,000					2,800,000				1,800,000
Accounts payable—affiliates						2,600,000					2,600,000				2,000,000
Prepaid assets - affiliates (less than)						100,000					100,000				$ 200,000
Affiliated Entity | Retailco
Related Party Transaction [Line Items]
Service contract term				1 year
Service contract, renewal term				1 year
Affiliated Entity | Purchased Natural Gas From Affiliate
Related Party Transaction [Line Items]
Cost of revenues						0		3,400,000			1,600,000		9,600,000
Affiliated Entity | Purchased Natural Gas Sold To Affiliate
Related Party Transaction [Line Items]
Net asset optimization revenues						0		300,000			200,000		900,000
Affiliated Entity | Marlin Transportation Agreement
Related Party Transaction [Line Items]
Retail cost of revenues (less than)					$ 100,000					$ 100,000
Affiliated Entity | Allocated Overhead Costs
Related Party Transaction [Line Items]
General and administrative expense - affiliates						3,200,000		$ 600,000			12,800,000		2,300,000
Affiliated Entity | Allocated Overhead Costs | Retailco
Related Party Transaction [Line Items]
General and administrative expense - affiliates						2,900,000					11,000,000
Affiliated Entity | Property and Equipment Capitalized | Retailco
Related Party Transaction [Line Items]
Amount capitalized for application, development and implementation of various systems						$ 200,000					1,300,000
NuDevco Retail and Retailco
Related Party Transaction [Line Items]
Payments of distributions to affiliates											$ 19,900,000		$ 11,700,000
Tax receivable agreement, net cash savings (as a percent)											85.00%
NuDevco Retail and Retailco | Payment of Income Taxes Incurred by the Company
Related Party Transaction [Line Items]
Payments of distributions to affiliates											$ 6,300,000
Retailco
Related Party Transaction [Line Items]
Payments of distributions to affiliates											10,100,000
NG&E
Related Party Transaction [Line Items]
Payments of distributions to affiliates											$ 9,800,000
NuDevco Retail Holdings and NuDevco Retail
Related Party Transaction [Line Items]
Tax receivable agreement, deferral period											5 years
Tax receivable agreement, coverage percentage											130.00%
Tax receivable agreement, target dividend (in dollars per share)											$ 0.3625
Common Class B
Related Party Transaction [Line Items]
Share price (in dollars per share)		$ 20	$ 20
Common Class B | Subsidiary of Common Parent | National Gas & Electric, LLC
Related Party Transaction [Line Items]
Number of shares issued for acquisition (shares)		2,000,000
Common Class B | Subsidiary of Common Parent | Retailco
Related Party Transaction [Line Items]
Number of shares issued for acquisition (shares)			699,742
Value of shares issued for acquisition			$ 14,000,000

[1] Financial information has been recast to include results attributable to the acquisition of Major Energy Companies by an affiliate on April 15, 2016. See Notes 2 and 3 "Basis of Presentation" and "Acquisitions," respectively, for further discussion.

[2] Net asset optimization (expenses) revenues includes asset optimization revenues—affiliates of $0 and $263 for the three months ended September 30, 2016 and 2015, respectively, and asset optimization revenues—affiliates cost of revenues of $0 and $3,382 for the three months ended September 30, 2016 and 2015, respectively and asset optimization revenues—affiliates of $154 and $928 for the nine months ended September 30, 2016 and 2015, respectively, and asset optimization revenue—affiliates cost of revenues of $1,633 and $9,589 for the nine months ended September 30, 2016 and 2015, respectively.

[3] Financial information has been recast to include results attributable to the acquisition of Oasis Power Holdings LLC from an affiliate on May 12, 2015. See Notes 2 "Basis of Presentation" for further discussion.

[4] Retail cost of revenues includes retail cost of revenues—affiliates of $0 for the three months ended September 30, 2016 and 2015, respectively, and less than $100 for the nine months ended September 30, 2016 and 2015 respectively.

[5] General and administrative includes general and administrative expense—affiliates of $3,078 and $0 for the three months ended September 30, 2016, and 2015, respectively, and $11,521 and $100 for the nine months ended September 30, 2016 and 2015, respectively.

[6] Financial information has been recast to include results attributable to the acquisition of the Major Energy Companies from an affiliate on August 23, 2016. See Notes 2 and 3 "Basis of Presentation" and "Acquisitions," respectively, for further discussion.

[7] Financial information has been recast to include results attributable to the acquisition of Oasis Power Holdings LLC by an affiliate on May 12, 2015. See Notes 2 "Basis of Presentation" for further discussion.